Lately I've been thinking that they might never open Gmail up for open enrollment; they might just stick to the invitation model. While that wouldn't solve the problem totally, at least it would limit it.

Just now I see that my stash of invitations has grown from the typical 6 to 50. Is this the real launch of Gmail? How many Gmail invitations do you see right now?

It would be fascinating to graph the pattern of Gmail invitations worldwide. I bet Google has the data from day one: who invited whom? Perhaps more importantly to Google: what mail service did they use previously? Hotmail, Yahoo, AOL...